arXiv subjects

I. A. Pshenichnov

Publications and source records attributed to I. A. Pshenichnov.

At least 19 recordsLinked to original sources

arXiv2025

Challenge of nuclear transmutation in heavy-ion colliders

We investigate the production of secondary nuclei in the hadronic fragmentation and electromagnetic dissociation (EMD) of $^{20}$Ne beams at the LHC and $^{124}$Xe beams at NICA. For light nuclei at LHC energies, our calculations show that hadronic interactions are the dominant channel for nuclear transmutation. This contrasts with the previously established dominance of EMD in $^{208}$Pb-$^{208}$Pb collisions. For $^{20}$Ne-$^{20}$Ne collisions at $\sqrt{s_{\rm NN}}=5.36$ TeV, we provide calculated cross sections and momentum distributions of produced nuclei such as $^4$He, $^{12}$C, $^{14}$N, and $^{16}$O. These results are essential for assessing potential contamination of the $^{20}$Ne-$^{20}$Ne event sample by collisions involving other nuclear species. Secondary nuclei will be also produced in the EMD of $^{124}$Xe beams at NICA, but they will not contaminate $^{124}$Xe-$^{124}$Xe data.

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arXiv2025

Benchmarking Hadronic Models in Geant4 for Detector Simulations

The construction of modern detectors used in high-energy physics experiments is typically guided by modeling with the Geant4 toolkit to evaluate detector performance in terms of geometrical acceptance and detection efficiency. Several hadronic models are available in Geant4 for modeling nuclear reactions induced by fast nucleons. It is shown that they result in different multiplicity and charge distributions of secondary particles and nuclear fragments. The impact of these differences on modeling the Highly-Granular Neutron Detector (HGND) prototype for the BM@N experiment at Nuclotron-based Ion Collider fAcility (NICA) is evaluated.

physics.ins-det↗

arXiv2025

Production of spectator neutrons, protons and light fragments on fixed targets at NICA

The Ultrarelativistic Quantum Molecular Dynamics (UrQMD) model was connected to a set of models called Ablation Monte Carlo (AMC) to identify excited spectator fragments on completion of the UrQMD modeling of nucleus-nucleus collisions and then simulate spectator decays. The UrQMD-AMC approach combines the Minimum Spanning Tree (MST) clustering algorithm, which associates individual nucleons with excited clusters termed prefragments, with decay models of excited nuclei from the Geant4 toolkit. The relevant decay model for the prefragments decay is selected based on their mass and excitation energy, and includes nuclear evaporation, statistical multifragmentation, and Fermi breakup models. The UrQMD-AMC approach was validated by comparing its results with data on the rapidity and transverse momentum distributions of neutrons and light fragments from 600A MeV Sn + Sn and 10.6A GeV Au + Ag collisions. This approach supplements the evolution of individual nucleons during a nucleus-nucleus collision simulated with UrQMD with nucleon clustering to simulate also the production of spectator nuclear fragments, which are not produced in the UrQMD model alone.

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arXiv2024

Calculations of the cell survival rate after irradiating with minibeams of protons and $^{12}$C

The propagation of minibeams of protons and $^{12}$C in a water phantom was modelled with Geant4 v10.3, and the survival probabilities of human salivary gland cells representing healthy and tumour tissues of normal radiosensitivity were calculated with the modified microdosimetric kinetic model. The advantage of minibeams over homogeneous irradiation in sparing healthy tissues proximal to the tumour was demonstrated. Survival-volume histograms were proposed to quantify the difference in the survival probability of cells inside and outside the minibeam spots.

physics.med-ph↗

arXiv2023

Proton and carbon-ion minibeam therapy: from modeling to treatment

Arrays of minibeams of protons and $^{12}$C in tissue-like media were modeled with Geant4 toolkit. A set of beam energies was used in simulations to provide a Spead-out Bragg peak (SOBP) extended by 6 cm in depth for protons as well as for $^{12}$C. In both cases, beams of 0.3 mm or 0.5 mm FWHM were arranged at the entrance to a water phantom either on a rectangular or an hexagonal grid to compare two kinds of projectiles and different minibeam patterns. Differential and cumulative dose-volume histograms (DVH) were calculated and compared for protons and $^{12}$C as dose uniformity metrics. A uniform dose distribution was easily achieved with protons due to an enhanced lateral scattering of these projectiles in comparison to $^{12}$C. The cumulative DVHs calculated for 0.3 mm or 0.5 mm minibeams almost coincide in the target volume, but diverge for different grid patterns. In contrast, cumulative entry DVHs were found similar for both grid patterns, but different for 0.3 mm and 0.5 mm minibeams.

physics.med-ph↗

arXiv2023

Production of various elements in ultraperipheral $^{208}$Pb-$^{208}$Pb collisions at the LHC

As predicted by theory and confirmed by measurements, one, two or three neutrons are emitted frequently in ultraperipheral collisions (UPCs) of heavy relativistic nuclei, in particular, $^{208}$Pb. The exchange of low-energy Weizsäcker--Williams photons dominates in such interactions. This leads to the excitation and decay of Giant Dipole Resonances (GDR) in colliding nuclei below the proton emission threshold. Less is known about the electromagnetic dissociation of $^{208}$Pb induced by energetic photons leading to violent fragmentation of $^{208}$Pb. The UPCs of lead nuclei at the LHC were modelled with Relativistic ELectromagnetic Dissociation (RELDIS) model to evaluate the contribution of photonuclear reactions in the domain of quasideuteron absorption and at higher photon energies. It was demonstrated that due to the presence of a single heavy residue in the final state mostly accompanied by free protons and neutrons, the cross sections of the production of specific elements can be well approximated by the proton emission cross sections, which can be measured in the ALICE experiment at the LHC.

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arXiv2013

Measurement of the total cross section of uranium-uranium collisions at $\sqrt{s_{NN}}=192.8$ GeV

Heavy ion cross sections totaling several hundred barns have been calculated previously for the Relativistic Heavy Ion Collider (RHIC) and the Large Hadron Collider (LHC). These total cross sections are more than an order of magnitude larger than the geometric ion-ion cross sections primarily due to Bound-Free Pair Production (BFPP) and Electro-Magnetic Dissociation (EMD). Apart from a general interest in verifying the calculations experimentally, an accurate prediction of the losses created in the heavy ion collisions is of practical interest for the LHC, where some collision products are lost in cryogenically cooled magnets and have the potential to quench these magnets. In the 2012 RHIC run uranium ions collided with each other at $\sqrt{s_{NN}} = 192.8$ GeV with nearly all beam losses due to collisions. This allows for the measurement of the total cross section, which agrees with the calculated cross section within the experimental error.

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arXiv2013

Emission of forward neutrons by 158A GeV indium nuclei in collisions with Al, Cu, Sn and Pb

The cross sections of forward emission of one, two and three neutrons by 158A GeV 115In nuclei in collisions with Al, Cu, Sn and Pb targets are reported. The measurements were performed in the framework of the ALICE-LUMI experiment at the SPS facility at CERN. Various corrections accounting for the absorption of beam nuclei and produced neutrons in target material and surrounding air were introduced. The corrected cross section data are compared with the predictions of the RELDIS model for electromagnetic fragmentation of 115In in ultraperipheral collisions, as well as with the results of the abrasion-ablation model for neutron emission in hadronic interactions. The measured neutron emission cross sections well agree with the RELDIS results, with the exception of In-Al collisions where the measured cross sections are larger compared to RELDIS. This is attributed to a relatively large contribution of hadronic fragmentation of In on Al target with respect to electromagnetic fragmentation, on the contrary to similar measurements performed earlier with 30A GeV 208Pb colliding with Al.

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arXiv2010

Transport calculations of antiproton-nucleus interactions

The Giessen Boltzmann-Uehling-Uhlenbeck transport model is extended and applied to the antiproton-nucleus interactions in a wide beam momentum range. The model calculations are compared with the experimental data on $\bar p$-absorption cross sections on nuclei with an emphasis on extraction of the real part of an antiproton optical potential. The possibility of the cold compression of a nucleus by an antiproton in-flight is also considered.

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arXiv2009

Antiproton-nucleus collisions simulation within a kinetic approach with relativistic mean fields

The Giessen Boltzmann-Uehling-Uhlenbeck transport model with relativistic mean fields is used to simulate $\bar p$-nucleus collisions. Antiproton absorption cross sections and momentum distributions of annihilation products are calculated by varying the $\bar p$ coupling strength to the mean meson fields. Parameters of the antiproton-nucleus optical potential are extracted from the comparison of the model calculations with experimental data.

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arXiv2008

Pion emission in 2H, 12C, 27Al, gamma pi+ reactions at threshold

The first data from MAX-lab in Lund, Sweden on pion production in photonuclear reactions at threshold energies, is presented. The decrease of the total yield of pi+ in gamma + 12C, 27Al reactions below 200 MeV as well as differential, dsigma/dOmega, cross sections follow essentially predictions from an intranuclear cascade model with an attractive potential for pion-nucleus interaction in its simplest form. Double differential, d2sigma/dOmegadT, cross sections at 176 MeV show, however, deviations from the model, which call for refinements of nuclear and Coulomb potentials and possibly also for coherent pion production mechanisms.

nucl-ex↗

arXiv2007

The Physics of Ultraperipheral Collisions at the LHC

We discuss the physics of large impact parameter interactions at the LHC: ultraperipheral collisions (UPCs). The dominant processes in UPCs are photon-nucleon (nucleus) interactions. The current LHC detector configurations can explore small $x$ hard phenomena with nuclei and nucleons at photon-nucleon center-of-mass energies above 1 TeV, extending the $x$ range of HERA by a factor of ten. In particular, it will be possible to probe diffractive and inclusive parton densities in nuclei using several processes. The interaction of small dipoles with protons and nuclei can be investigated in elastic and quasi-elastic $J/ψ$ and $Υ$ production as well as in high $t$ $ρ^0$ production accompanied by a rapidity gap. Several of these phenomena provide clean signatures of the onset of the new high gluon density QCD regime. The LHC is in the kinematic range where nonlinear effects are several times larger than at HERA. Two-photon processes in UPCs are also studied. In addition, while UPCs play a role in limiting the maximum beam luminosity, they can also be used a luminosity monitor by measuring mutual electromagnetic dissociation of the beam nuclei. We also review similar studies at HERA and RHIC as well as describe the potential use of the LHC detectors for UPC measurements.

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arXiv2003

Evaluation of the total photoabsorption cross sections for actinides from photofission data and model calculations

We have calculated the fission probabilities for 237-Np, 233,235,238-U, 232-Th, and nat-Pb following the absorption of photons with energies from 68 MeV to 3.77 GeV using the RELDIS Monte-Carlo code. This code implements the cascade-evaporation-fission model of intermediate-energy photonuclear reactions. It includes multiparticle production in photoreactions on intranuclear nucleons, pre-equilibrium emission, and the statistical decay of excited residual nuclei via competition of evaporation, fission, and multifragmentation processes. The calculations show that in the GeV energy region the fission process is not solely responsible for the entire total photoabsorption cross section, even for the actinides: ~55-70% for 232-Th, \~70-80% for 238-U, and ~80-95% for 233-U, 235-U, and 237-Np. This is because certain residual nuclei that are created by deep photospallation at GeV photon energies have relatively low fission probabilities. Using the recent experimental data on photofission cross sections for 237-Np and 233,235,238-U from the Saskatchewan and Jefferson Laboratories and our calculated fission probabilities, we infer the total photoabsorption cross sections for these four nuclei. The resulting cross sections per nucleon agree in shape and in magnitude with each other. However, disagreement in magnitude with total-photoabsorption cross-section data from previous measurements for nuclei from C to Pb calls into question the concept of a ``Universal Curve'' for the photoabsorption cross section per nucleon for all nuclei.

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arXiv2003

Relativistic heavy ion collider as a photon factory: from GDR excitations to vector meson production

A variety of phenomena, which reveal itself in distant collisions of ultrarelativistic nuclei is discussed. One or both nuclei may be disintegrated in a single collision event by the long-range electromagnetic forces due to the impact of the Lorentz-boosted Coulomb fields of collision partners.The process is considered in the framework of the Weizsäcker-Williams method and simulated by the RELDIS code, which takes into account all possible channels of nuclear disintegration, including multiple neutron and proton emission and meson production. Mutual electromagnetic dissociation of nuclei in peripheral collisions can best be studied at RHIC and LHC. The contributions of next-to-leading-order processes with multiple photon absorption of equivalent photons by collision partners are considered in detail. As demonstrated, the rates of the correlated forward-backward 2n and 3n emission are very sensitive to the presence of double and triple excitations of Giant Resonances in colliding nuclei. A practical application consists in the possibility of beam luminosity monitoring in colliders via the registration of the correlated 1n and 2n emission in mutual electromagnetic dissociation.

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arXiv2001

Mutual heavy ion dissociation in peripheral collisions at ultrarelativistic energies

We study mutual dissociation of heavy nuclei in peripheral collisions at ultrarelativistic energies. Earlier this process was proposed for beam luminosity monitoring via simultaneous registration of forward and backward neutrons in zero degree calorimeters at Relativistic Heavy Ion Collider. Electromagnetic dissociation of heavy ions is considered in the framework of the Weizsacker-Williams method and simulated by the RELDIS code. Photoneutron cross sections measured in different experiments and calculated by the GNASH code are used as input for the calculations of dissociation cross sections. The difference in results obtained with different inputs provides a realistic estimation for the systematic uncertainty of the luminosity monitoring method. Contribution to simultaneous neutron emission due to grazing nuclear interactions is calculated within the abrasion model. Good description of CERN SPS experimental data on Au and Pb dissociation gives confidence in predictive power of the model for AuAu and PbPb collisions at RHIC and LHC.

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arXiv2000

Simultaneous Heavy Ion Dissociation at Ultrarelativistic Energies

We study the simultaneous dissociation of heavy ultrarelativistic nuclei followed by the forward-backward neutron emission in peripheral collisions at colliders. The main contribution to this particular heavy-ion dissociation process, which can be used as a beam luminosity monitor, is expected to be due to the electromagnetic interaction. The Weizsacker-Williams method is extended to the case of simultaneous excitation of collision partners which is simulated by the RELDIS code. A contribution to the dissociation cross section due to grazing nuclear interactions is estimated within the abrasion model and found to be relatively small.

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arXiv2000

Inclusive meson production in peripheral collisions of ultrarelativistic heavy ions

There exist several proposals to use Weizsäcker-Williams photons generated by ultrarelativistic heavy ions to produce exotic particles in $γγ$ fusion reactions. To estimate the background conditions for such reactions we analyze various mechanisms of meson production in very peripheral collisions of ultrarelativistic heavy ions at RHIC and LHC energies. Besides $γγ$ fusion they include also electromagnetic $γA$ interactions and strong nucleon-nucleon interactions in grazing $AA$ collisions. All these processes are characterised by low multiplicities of produced particles. $γA$ and $AA$ events are simulated by corresponding Monte Carlo codes, RELDIS and FRITIOF. In each of these processes a certain fraction of pions is produced close to the mid-rapidity region that gives a background for the $γγ$ events. The possibility of selecting mesons produced in $γγ$ fusion events via different $p_t$ cut procedures is demonstrated.

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arXiv1999

Nuclear disintegration induced by virtual photons at heavy-ion colliders

A model of electromagnetic interaction of relativistic heavy ions which makes it possible to calculate the inclusive and exclusive characteristics of such interactions is presented. The multistep model includes (1) the single and double virtual photon absorption by a nucleus, (2) intranuclear cascades of produced hadrons and (3) statistical decay of excited residual nuclei described by evaporation, fission and multifragmentation mechanisms. Components of the model were verified by comparison of calculation results with experimental data obtained with monoenergetic photons and heavy ions at KEK-Tanashi Synchrotron and CERN SPS accelerator, respectively.

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